A:  The Urantia Book doesn’t speak directly about masturbation or the rightness or wrongness of most things—this is left up to our own understanding. Here are two quotes from the book that may help to provide some insight:

Let man enjoy himself; let the human race find pleasure in a thousand and one ways; let evolutionary mankind explore all forms of legitimate self gratification, the fruits of the long upward biologic struggle. Man has well earned some of his present day joys and pleasures. But look you well to the goal of destiny! Pleasures are indeed suicidal if they succeed in destroying property, which has become the institution of self maintenance; and self gratifications have indeed cost a fatal price if they bring about the collapse of marriage, the decadence of family life , and the destruction of the home—man’s supreme evolutionary acquirement and civilization’s only hope of survival. (84:8.7)

Someday man should learn how to enjoy liberty without license, nourishment without gluttony, and pleasure without debauchery. Self control is a better human policy of behavior regulation than is extreme self denial. Nor did Jesus ever teach these unreasonable views to his followers. (89:3.7)